Anatomy of Hearing - A&P

what is the “business” of hearing

1. transduction of sound from acoustical → mechanical energy.

2. transduction of mechanical energy → electrochemical energy.

3. transmission and interpretation of electrochemically produced signal.

what consists of the outer ear

pinna, external auditory canal

label the parts of the pinna

how is the external ear canal shaped

‘s’ shape

outer ___ of the external ear canal is cartilage; the inner ___ is bony

1/3; 2/3

what do you see when you look into the EAM

hair, cerumen, tympanic membrane

the cartilagenous portion of the EAM has ____ and ____ that make cerumen

hair; glands

what is the arrow pointing to

the bony part of the EAM

what consists of the middle ear

ossicles, tympanic membrane, oval window

the tympanic membrane is NOT part of the

outer ear

label the parts of the tympanic membrane

describe the tympanic membrane

• concave oval

• very small mass, high compliance

• attaches to the malleus

  • landmarks: manubrium of malleus and umbo

what is the malleus

first middle ear ossicle

what is the cone of light

the reflection of an otoscope light

where would the cone of light be in the right ear

on the right side

where would the cone of light be in your left ear

on the left side

what are the three layers of epithelium in the tympanic membrane

• outer layer continuous w EAM

• middle layer = strong fibrous tissue

• inner layer continuous w middle ear cavity

what is the middle ear space

air filled cavity called the tympanic cavity

what are the three ossicles

• malleus

• incus

• stapes

the tympanic cavity contains the ____

ossicles

label the three ossicles

left: malleus

right: incus

bottom: stapes

what are the two parts of the tympanic membrane

• pars tensa: stretched, lower part of the membrane

• pars flaccida: upper part, loose and thin

what are the two middle ear muscles

• tensor tympani: enters middle ear space from the anterior wall and attaches to the malleus

• stapedius muscle: enters the middle ear space from the posterior wall and attaches to the stapes

what is the function of the middle ear muscles

to stiffen the middle ear transmission system

where is the eustachian tube located

on the front/ anterior wall of the middle ear